In the United States alone, at least 45 million people are afflicted with chronic eating and/or weight disorders, such as anorexia nervosa, bulimia and obesity, all of which are associated with increased mortality and morbidity. Although their etiology is complex and multifaceted, it is likely that these disorders result in part from the abnormal expression of hypothalamic neurochemical systems that are involved in regulation of natural eating behavior. Using a metabolic tracer we are elucidating the neural circuitry of this system. To assist us in processing this data, we are collaborating with the Resource on testing of a rat probabilty brain atlas